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[log in to unmask]" type="cite">[1 0]
This will give you the response to your regressor.
[1 -1] would be the difference between the weight of the regressor and its first derivative, which is meaningless.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School
Office: (773) 406-2464
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On Sat, Nov 13, 2010 at 3:40 PM, Anders Eklund <[log in to unmask]> wrote:
Dear SPMers,
I have a simple question regarding the contrast vector in the GLM. I have a single subject dataset where the subject periodically (20 s activity, 20 s rest) performed a task. As regressors I use the square wave paradigm convolved with the heamodynamic response function (difference of gammas) and it's temporal derivative. Should the contrast vector be [1 -1], [1 0] or something else?
/Anders